Decoupling Analysis of Interaction between Tunnel Surrounding Rock and Support in Xigeda Formation Strata

Ping Zhou,Feicong Zhou,Jiayong Lin,Jinyi Li,Yifan Jiang,Bao Yang,Zhijie Wang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

The Xigeda Formation has the characteristics of poor cementation, variable structure, and softening in water. It is prone to lead to failure of the initial support structures, arch collapse, and even roof fall. The key to the problem lies in the exploration of the interaction between surrounding rock and support. Therefore, based on the constraint loss theory of the tunnel face space effect, this paper constructively introduces multiple dependent variables, including the intermediate principal stress, the dilatancy of the surrounding rock, the timeliness of the shotcrete support stiffness, and the water content of the Xigeda formation, to decouple the whole process of the interaction between the surrounding rock and support, and discusses the influence of each variable. The research results show that: i) there is a critical support point in the tunnel under the influence of the unified strength theoretical parameter b and water content, and when the unified strength theoretical parameter b is constant, the critical distance of the support will decrease with the increase of the water content; ii) from the perspective of deformation control, the stress of support structure will increase with the increase of dilatancy angle of Xigeda surrounding rock; iii) considering the hardening characteristics of shotcrete, the initial support stiffness of Xigeda tunnel increases nonlinearly, and the whole process of stress and deformation can be divided into four stages; iv) the combined support structure of section steel and grille has little difference in the deformation control effect of the surrounding rock and the stress of the support structure, but the combined support structure of the grille steel frame is more sensitive to the hardening parameters.

Key Parameters Design Method of AGF Method for Metro Connecting Passage in Water-Rich Coastal Area

Feicong Zhou,Ping Zhou,Jinyi Li,Tiancheng Ge,Jiayong Lin,Zhijie Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Artificial Ground Freezing Method (AGF) is an efficient, environmentally friendly reinforcement method for the construction of metro connecting passage in water-rich and weak stratum. The core of AGF is the design of frozen wall thickness and freezing temperature. In order to obtain the quantitative relationship between the freezing temperature and the frozen wall thickness, this study firstly equates the frozen wall to a rectangular frame mechanical model based on the stress state of the frozen wall formed by AGF. And then the calculation method of frozen wall thickness based on strength conditions is obtained by theoretical estimation. Furthermore, based on the relationship between the strength of the frozen soil and the freezing temperature obtained from the experiment, the freezing temperature and the frozen wall thickness are related to propose a frozen wall thickness design method considering the freezing temperature. In addition, experimental studies revealed that the compressive strength and shear strength of frozen soil increase linearly as the freezing temperature decreases. Secondly, the lower the freezing temperature, the smaller the frozen wall thickness required. Notably, the relationship between the frozen wall thickness and freezing temperature formed by the AGF method can be obtained through the design method proposed in this paper. Taking actual case as an example, when the frozen wall thickness is selected from 1.2 to 2.2 m, the required freezing temperature range is (-5) to (-25)oC. Finally, the feasibility of the designed freezing parameters in the connecting passage construction is verified through numerical simulation and field measurement, which shows that the design method has a promotion prospect.

Characterization of ginsenoside compound K loaded ionically cross-linked carboxymethyl chitosan―calcium nanoparticles and its cytotoxic potential against prostate cancer cells

Jianmei Zhang,Jinyi Zhou,Qiaoyun Yuan,Changyi Zhan,Zhi Shang,Qian Gu,Ji Zhang,Guangbo Fu,Weicheng Hu 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.2

Backgroud: Ginsenoside compound K (GK) is a major metabolite of protopanaxadiol-type ginsenosides and has remarkable anticancer activities in vitro and in vivo. This work used an ionic cross-linking method to entrap GK within O-carboxymethyl chitosan (OCMC) nanoparticles (Nps) to form GK-loaded OCMC Nps (GK―OCMC Nps), which enhance the aqueous solubility and stability of GK. Methods: The GK―OCMC Nps were characterized using several physicochemical techniques, including x-ray diffraction, transmission electron microscopy, zeta potential analysis, and particle size analysis via dynamic light scattering. GK was released from GK―OCMC Nps and was conducted using the dialysis bag diffusion method. The effects of GK and GK―OCMC Nps on PC3 cell viability were measured by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Fluorescent technology based on Cy5.5-labeled probes was used to explore the cellular uptake of GK―OCMC Nps. Results: The GK―OCMC NPs had a suitable particle size and zeta potential; they were spherical with good dispersion. In vitro drug release from GK―OCMC NPs was pH dependent. Moreover, the in vitro cytotoxicity study and cellular uptake assays indicated that the GK―OCMC Nps significantly enhanced the cytotoxicity and cellular uptake of GK toward the PC3 cells. GK―OCMC Nps also significantly promoted the activities of both caspase-3 and caspase-9. Conclusion: GK―OCMC Nps are potential nanocarriers for delivering hydrophobic drugs, thereby enhancing water solubility and permeability and improving the antiproliferative effects of GK.

Firm size affecting efficiency of production and commercialization of knowledge: embedded in cluster development

Li Yawen,Zhong Zhou,Guan Jiancheng,Zhou Jinyi,Li Jizhen 기술경영경제학회 2020 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.28 No.1

This study examines the impact of platform innovation on the efficiency of firms located in different clusters. The sample contains data for 1,257 firms from 2005 to 2015 in Beijing’s Zhongguancun Science Park, which is known as China’s ‘Silicon Valley’. Using the DEA model to gauge the efficiency of each firm over time, we found that firm size has a significantly negative correlation with knowledge production efficiency, a significantly positive correlation with its knowledge commercialisation efficiency, and an inverted-U shaped relationship with overall efficiency. We then explored the mediating effect of firm size on the relationship between the characteristics of clusters and firm efficiency, before concluding with both managerial and academic implications.

Reformability evaluation of blasting-enhanced permeability in in situ leaching mining of low-permeability sandstone-type uranium deposits

Wang Wei,Liang Xuanyu,Niu Qinghe,Wang Qizhi,Zhuo Jinyi,Su Xuebin,Zhou Genmao,Zhao Lixin,Yuan Wei,Chang Jiangfang,Zheng Yongxiang,Pan Jienan,Wang Zhenzhi,Ji Zhongmin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

It is essential to evaluate the blasting-enhanced permeability (BEP) feasibility of a low-permeability sandstone-type uranium deposit. In this work, the mineral composition, reservoir physical properties and rock mechanical properties of samples from sandstone-type uranium deposits were first measured. Then, the reformability evaluation method was established by the analytic hierarchy process-entropy weight method (AHP-EWM) and the fuzzy mathematics method. Finally, evaluation results were verified by the split Hopkinson Pressure Bar (SHPB) experiment and permeability test. Results show that medium sandstone, argillaceous sandstone and siltstone exhibit excellent reformability, followed by coarse sandstone and fine sandstone, while the reformability of sandy mudstone is poor and is not able to accept BEP reservoir stimulation. The permeability improvement and the distribution of damage fractures before and after the SHPB experiment confirm the correctness of evaluation results. This research provides a reformability evaluation method for the BEP of the low-permeability sandstone-type uranium deposit, which contributes to the selection of the appropriate regional and stratigraphic horizon of the BEP and the enhanced ISL of the low-permeability sandstone-type uranium deposit.